Masteries

Offense:
9

Defense:
0

Utility:
21

Hello Mobafire,

Welcome to my Kassadin build. I made this build because the high rated Kassadin wasn't complete to me and because Kassadin is my favorite character. He's strong, he looks cool, he's fast and he's hard to kill when followed.

Cons:
- Very weak in the beginning
- Slow farmer in the beginning
- Low HP

How to play with him:

Early game:
Kassadin is very fragile at the start. Start with a mana crystal and a health potion. You can choose 2 things now, lvling up your Null Sphere so you can hit enemy characters or creeps sometimes, or you can lvl Force Pulse for when an enemy comes close to you. Keep playing defensive until you are lvl 6. Try to buy a Tear of the Goddess as fast as possible so you can stack up the mana. You will need it when it's time to kickass.
Buy Boots and a Mejai's Soulstealer when you can.

Mid game:
Ok, you are lvl 6 now. You should have Tear of the Goddes, boots and maybe a Mejai's Soulstealer. It's time to kick their ***. Keep casting your Null Sphere to get the enemy on lower health. You can also use Force Pulse if you are sure you get it full right on time. If the enemy is low on health, charge your Force Pulse until it's full, be sure you got enough mana to cast Null Sphere, Force Pulse and Rift Walk (maybe 2x).
If you see someone with low health, first do Rift Walk to surprise him, then do Null Sphere so he can't do anything to you and then you do Force Pulse for epic damage and slow. If he flees, Just cast another Riftwalk for more damage, watch your mana though. No mana means certain death.
By the time, buy parts for a Lich Bane which is one of the best items for Kassadin.

Late game:
Now just go FULL AP and some health. Complete the Tear of the Goddes to a Archangel's Staff. Buy a Zhonya's Ring, woah guys I love this, you are just KICKING their *** now. For more survivability buy Banshees Veil, it rocks and you will be unstoppable.

Summoner's Skill:
Early game mana is a must for Kassadin, so that's why I pick clarity. You can spam a lot more and they will fear you what gives you a perfect opportunity to farm a lot. :)
My other skill is Exhaust. Good for the team, it slows and it's good for your defense. When you got ambushed by an epic DPS character, you can just cast Exhaust on him, then you do Rift Walk (or kill him) to flee! Woah, they will hate you.